Modern phones provide myriad conveniences but provide many opportunities for unwanted or unsolicited communications. For example, telemarketers and robocalls can originate unwanted calls. Call blocking, call screening, or call rejection have been used to block incoming calls from specific telephone numbers. For example, some prior art call blocking techniques have included external call blockers that plug into existing phones allowing user to send a message to such unwanted callers. Other prior art techniques have implemented call blocking by storing blocked numbers in a SIM (subscriber identity module) installed in a phone. However, when a user changes phones, the call blocking may not transfer to any such new devices. Further, it can be cumbersome to track and block numbers individually to cover all cases of unwanted numbers.